kikaha.core.cdi.helpers.ManyElementsProvidableField Maven / Gradle / Ivy

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package kikaha.core.cdi.helpers;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Collection;

import javax.enterprise.inject.Typed;

import kikaha.core.cdi.DefaultServiceProvider.DependencyInjector;
import kikaha.core.cdi.helpers.filter.Condition;
import kikaha.core.cdi.helpers.filter.QualifierCondition;
import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor
@SuppressWarnings( { "unchecked" } )
public class ManyElementsProvidableField implements ProvidableField {

	final Field field;
	final Class fieldType;
	final Condition condition;

	@Override
	public void provide( Object instance, DependencyInjector provider ) throws Throwable {
		final Object value = provider.loadAll( fieldType, condition );
		set( instance, value );
	}

	public void set( final Object instance, final Object value ) throws IllegalArgumentException, IllegalAccessException {
		field.set( instance, value );
	}

	public static  ProvidableField from( Collection> qualifiers, final Field field ) {
		assertFieldTypeIsIterable( field );
		field.setAccessible( true );
		final Class collectionType = identifyWhichTypeThisCollectionHas(field);
		return new ManyElementsProvidableField<>(
				field, (Class)collectionType, new QualifierCondition<>( qualifiers ) );
	}

	private static void assertFieldTypeIsIterable( final Field field ) {
		if ( !DefaultFieldQualifierExtractor.fieldRepresentsACollection( field ) )
			throw new IllegalStateException( "Field " + field.getName() + " expects to have Iterable type." );
	}

	private static Class identifyWhichTypeThisCollectionHas( final Field field ){
		final Typed annotation = field.getAnnotation( Typed.class );
		return annotation.value()[0];
	}
}